Power Transmission Devices
• Belt drive,
• chain drive,
• gear drive
Chain Drive
In belt drives, slipping
of belt may occur.
In
order
avoid
slipping, steel chains
are used,
The chains are made
up of rigid links which
are hinged together in
order to avoid the
necessary flexibility
for warping around
the driving and driven
wheels.
The wheels have projecting teeth and fit into
the corresponding recesses, in the links of
The chain.
The wheels and the chain are constrained to
move together without slipping and ensures
perfect velocity ratio.
The toothed wheel are known as sprocket
wheels or simply sprockets.
These wheels resemble to spur gears
Link Chain
These chains are used for hoisting and hauling purposes.
The links of this type of chain are of oval or square shape.
The joint of each link is welded. The sprockets which are used
for this type of chain have receptacles to receive the links.
Such type of chains are used only at low speeds such as in chain
hoists and in anchors for marine works, cranes and dredges.
Block Chain
These chains are used for transmission of power, when the distance
between the centers of shafts is short. These chains have provision for
efficient lubrication.
A block or bush chain is shown in figure. This type of chain was used
in the early stages of development in the power transmission.
It produces noise when approaching or leaving the teeth of the
sprocket because of rubbing between the teeth and the links. Such type
of chains are used to some extent as conveyor chain at small speed.
Roller Chain
 A roller chain consists of outer plates or pin link plates, inner
plates or roller link plates, pins, bushes and rollers. A pin
passes through the bush which is secured in the holes of the
roller between the two sides of the chain. The rollers are free
to rotate on the bush which protect the sprocket wheel teeth
against wear. The pins, bushes and rollers are made of alloy
steel.
Advantages of Chain Drive over Belt Drive
• As no slip takes place during chain drive, perfect
velocity ratio is obtained.
• Since the chains are made of metal, therefore they
occupy less space in width than a belt or rope drive.
• The chain drives can be used when the distance
between the shafts is less.
• It has high power transmitting capacity than belt
drive.
• It gives high transmission efficiency (Upto 98%).
• The chain drive gives less load on the shafts.
• A number of shafts can be driven in the same or
opposite direction by means of chain from a single
driving sprocket.
• It permits high speed reduction ratio upto 10 : 1 in
one step.
• It can be operated under adverse temperature and
atmospheric conditions.
• Chain drives are more compact than belt drive
Dis-advantages of Chain Drive over Belt Drive
1. Compared with belt drives, chain drive require precise alignment
of shafts.
2. Compared with belt drives, chain drives require proper
maintenance, particularly lubrication and slack adjustment.
3. The production cost of chain is relatively high.
4. They generate noise.
Application Chain Drive
1.
Bicycles, motor cycles
2.
Agriculture machinery
3.
Conveyors
4.
Rolling mills
5.
Road rollers
6.
Metal and wood working machinery
7.
Textile industry
8.
Building construction
9.
Material handling equipment